[英]C# “InvalidCastException” when trying to access webbrowser control from TimerCallback
[英]InvalidCastException when using webbrowser and threads in c#
当我尝试在backgroundWorker.DoWork函数中使用webBrowser组件时,出现以下异常:
用户代码未处理System.InvalidCastException
http://i.stack.imgur.com/EJFT3.jpg
这是我的代码:
void m_oWorker_DoWork(object sender, DoWorkEventArgs e)
{
//NOTE : Never play with the UI thread here...
string line;
//time consuming operation
while ((line=sr.ReadLine()) != null ){
int index = line.IndexOf(":");
HtmlDocument doc = web.Document;
Thread.Sleep(1000);
m_oWorker.ReportProgress(cnt);
//If cancel button was pressed while the execution is in progress
//Change the state from cancellation ---> cancel'ed
if (m_oWorker.CancellationPending)
{
e.Cancel = true;
m_oWorker.ReportProgress(0);
return;
}
cnt++;
}
//Report 100% completion on operation completed
m_oWorker.ReportProgress(100);
}
还是他们在c#中使用线程的另一种方式?
原因是当我在主界面中使用Thread.sleep方法时,gui冻结了!
WebBrowser不喜欢从其他线程访问。 尝试像这样将其传递给RunWorkerAsync():
private void button1_Click(object sender, EventArgs e)
{
HtmlDocument doc = web.Document;
m_oWorker.RunWorkerAsync(doc);
}
void m_oWorker_DoWork(object sender, DoWorkEventArgs e)
{
HtmlDocument doc = (HtmlDocument)e.Argument;
//NOTE : Never play with the UI thread here...
string line;
//time consuming operation
while ((line = sr.ReadLine()) != null)
{
int index = line.IndexOf(":");
Thread.Sleep(1000);
m_oWorker.ReportProgress(cnt);
//If cancel button was pressed while the execution is in progress
//Change the state from cancellation ---> cancel'ed
if (m_oWorker.CancellationPending)
{
e.Cancel = true;
m_oWorker.ReportProgress(0);
return;
}
cnt++;
}
//Report 100% completion on operation completed
m_oWorker.ReportProgress(100);
}
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